1. Field of the Invention
The present invention relates to a power steering device. In particular, the present invention relates to a power steering device, which is preferably used in an all terrain vehicle.
2. Description of Background Art
A power steering device according to the background art is shown in FIG. 3 of the present invention.
The power steering device shown in this figure includes a power assist cylinder 3 arranged between a steering shaft 1 and a chassis frame 2. Furthermore, a control valve 4 is operated by the steering shaft 1 to control the power assist cylinder 3. An oil pump 5 is provided for pressurizing the operating oil supplied to the power assist cylinder 3. Finally, an oil tank 6 for storing the operating oil is of a surrounding atmosphere releasing type and is fixed to the chassis frame 2.
The, the oil pump 5, the oil tank 6 and the control valve 4 are connected to each other through three oil pipes 7.
However, the aforesaid background art is problematic, since the power assist cylinder 3, control valve 4, oil pump 5 and oil tank 6 are separately and individually arranged. Accordingly, the layout or the above elements is restricted when they are installed on the chassis frame 2.
In addition, since the oil tank 6 is of a surrounding atmosphere releasing type, it is possible that the surface of the oil in the oil tank 6 becomes unstable. Furthermore, it is possible that foreign materials enter the oil tank 6 from the outside.
The present invention has been invented in view of the problems found in the background art. It is an object of the present invention to provide a power steering device capable of increasing the degree of freedom in the layout of the various elements of the power steering device. Furthermore, it is an object of the present invention to provide a device, which can stabilize the surface of the oil in the oil tank and prevent foreign materials from entering into the oil tank.
The power steering device according to a first aspect of the present invention includes a power assist cylinder arranged between a steering shaft and a chassis frame. Furthermore, a control valve is operated by the steering shaft to control the power assist cylinder. An oil pump is provided for pressurizing operating oil supplied to the power assist cylinder. Finally, the oil tank is of a closed type and is integrally installed in the oil pump.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art from this detailed description.